1. Field of the Invention
The invention relates to computer networks and more particularly to an apparatus and method for caching web pages.
2. Description of the Related Art
Caching is a methodology which has been applied with great advantage in devices ranging from computers, peripheral devices, and web browsers. Caching involves maintaining copies of recently used data in an alternate memory location to the main memory in which the original data is stored. This alternate memory location is identified as a cache memory. Cache policies have been developed to deal with the issues surrounding the identification and resolution of a lack of coherance between the copy of a set of data in cache memory and the original data in main or other source memory. Foremost among these policies is the concern with identifying data that no longer corresponds with the corresponding data in main or source memory. Such data in cache memory is said to be non-coherant, stale, or old data.
In closely coupled systems such as computers, elaborate cache policies have been developed which deal with maintenance of coherancy between the copy in cache memory and the source data in main memory. Only recently has there been an interest in applying cache methodoligies to loosely coupled systems. A primary area of such interest involves the Internet. Current browsers maintain the last five or ten web pages in cache memory. The presence of this cache capability in browsers provides users faster access to recently viewed data. With the relatively long download times required for a web page this is no small advantage. There are however drawbacks to a browser cache. The cache is shallow, i.e. maintains only the last five or ten web pages. This is typically only a fraction of the pages that a typical Internet user will frequently visit. A second drawback to a browser cache is that the cached pages are in many cases stale, old or out-dated, in that they do not maintain coherancy with the source pages delivered from the data center and associated web servers therein from which they were supplied.
What is needed is are improvements in the area of the caching of web pages.